1. Field of the Invention
The present invention relates to a pen-shaped input device having variable stiffness of writing tip, especially to a pen-shaped input device having variable stiffness of writing tip in which a switch unit and a stagger unit are installed thereby capable of providing variable stiffness to a writing tip through the staggering structure.
2. Description of Related Art
For a writing tip of a conventional digital pen, the writing tip can be altered through changing the relative locations of a ferrite core and a sensing coil, wherein a rubber member is provided for controlling the pressing pressure and recovery for this stroke. The stiffness of the rubber member of a digital board available in the market is mainly determined based on a hard-core writing instrument such as a pencil or a pen used for sketch thereby satisfying the writing tip of the mentioned pen. However, the writing stroke of the hard-core writing instrument and that of a soft-core writing instrument such as a calligraphy brush or water-painting brush are very different, so when being used in a professional manner, the user would still be provided with the writing tip similar to the hard-core writing instrument even if different type of pen is adopted, and the feedback is distinctively different from the feedback provided by the soft-core writing instrument.
Take the Taiwan Utility Model NO. M393727 titled in “Digital calligraphy brush” for example, the digital calligraphy brush includes an electrical pen, a magnetic member and a sleeve, a first end of the electrical pen is formed in a conical shape, and a second end thereof is connected to the magnetic member, the interior of the electrical pen is installed with a sensor, the sleeve is sleeved with the electrical pen with a movable manner, and the sleeve is installed with a magnetic sensor corresponding to the magnetic member, when the electrical pen is used for writing or painting, the electrical pen generates a displacement relative to the sleeve, so the distance between the magnetic sensor and the magnetic member is altered, and a corresponding signal is generated and transferred to a computer, thereby enabling the computer to calculate and simulate the size and the stroke of calligraphy writing.
Take the Taiwan Utility Model NO. M241752 titled in “Multi-module digital pen” for example, the multi-module digital pen includes a pen body having a touch control pen head, and a pen sleeve module sleeved at the outer side of the pen body; the pen sleeve module is provided with a tube, and a writing pen head used for writing and disposed at one end of the tube; after the pen sleeve module and the pen body are assembled, the action force generated during the writing pen head being used for writing can be transferred to the touch control pen head, so different writing pen head can be adopted with respect to the pen holding habit of a user, writing strokes with various width can also be provided, thereby allowing the user to have the feelings of pen stroke and pen holding similar to a real pen. However, the mentioned digital pen can only provide a fixed stiffness, such disadvantage shall be improved.
In view of the disadvantage of the mentioned digital pen, the present invention provides a pen-shaped input device having variable stiffness of writing tip for improving said disadvantage.